Impedance-tuned termination assembly and connectors incorporating same

ABSTRACT

A termination structure for a cable connector having a pair of differential wire pairs and an associated ground wire utilizes a series of nests, or solder cups, that have their dimensions tailored to maintain a desired level of electrical performance. These nests are also arranged in a configuration to maintain the aforementioned electrical performance, and also position the ground and signal conductors of the cable in the termination area in the same position and orientation as they take in the cable.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of prior application Ser.No. 09/540,605 filed Mar. 31, 2000, issued as U.S. Pat. No. 6,454,605 onSep. 24, 2002, which is a continuation-in-part application of Ser. No.09/356,205, filed Jul. 16, 1999, now U.S. Pat. No. 6,280,209.

BACKGROUND OF THE INVENTION

The present invention relates generally to terminations for connectorsand more particularly to connectors used in connection with signalcables.

Many electronic devices rely upon transmission lines to transmit signalsbetween related devices or between peripheral devices and circuit boardsof a computer. These transmission lines incorporate signal cables thatare capable of high-speed data transmissions.

These signal cables may use what are known as one or more twisted pairsof wires that are twisted together along the length of the cable, witheach such twisted pair being encircled by an associated groundingshield. These twisted pairs typically receive complimentary signalvoltages, i.e., one wire of the pair may see a +1.0 volt signal, whilethe other wire of the pair may see a −1.0 volt signal. Thus, these wiresmay be called “differential” pairs, a term that refers to the differentsignals they carry. As signal cables are routed on a path to anelectronic device, they may pass by or near other electronic devicesthat emit their own electric field. These devices have the potential tocreate electromagnetic interference to transmission lines such as theaforementioned signal cables. However, this twisted pair constructionminimizes or diminishes any induced electrical fields and therebyeliminates electromagnetic interference.

In order to maintain electrical performance integrity from such atransmission line, or cable, to the circuitry of an associatedelectronic device, it is desirable to obtain a substantially constantimpedance throughout the transmission line, from circuit to circuit orto avoid large discontinuities in the impedance of the transmissionline. The difficulty of controlling the impedance of a connector at aconnector mating face is well known because the impedance of aconventional connector typically drops through the connector and acrossthe interface of the two mating connector components. Although it isrelatively easy to maintain a desired impedance through an electricaltransmission line, such as a cable by maintaining a specific geometry orphysical arrangement of the signal conductors and the grounding shield,an impedance drop is usually encountered in the area where a cable ismated to a connector. It is therefore desirable to maintain a desiredimpedance throughout the connector and its connection to the cable.

Typical signal cable terminations involve the untwisting of the wirepairs and the unbraiding of the braided shield wire surrounding the wirepairs. These wires are unbraided manually and this manual operationtends to introduce variability into the electrical performance. This iscaused by unbraiding the grounding shield wires, then typically twistingthem into a single lead and subsequently welding or soldering thetwisted tail of a connector terminal. This unbraiding and twisting oftenresults in moving the signal conductors and grounding shield out oftheir original state in which they exist in the cable. Thisrearrangement may lead to a decoupling of the ground and signal wiresfrom their original state that may result in an increase of impedancethrough the cable-connector junction. Moreover, this twisting introducesmechanical variability into the termination area in that although acable may contain multiple differential pairs, the length of theunbraided shield wire may vary from pair to pair. This variability andrearrangement changes the physical characteristics of the system in thetermination area which may result in an unwanted change (typically anincrease) in the impedance of the system in the area.

Additionally, it is common for the signal and ground termination tailsof a connector to be arranged into whatever convenient space is presentat the connector mounting face without any control of the geometry orspatial aspects of the signal and ground terminals being considered.When signal wires and ground shields are pulled apart from the end of acable, an interruption of the cable geometry is introduced. It istherefore desirable to maintain this geometry in the termination areabetween the cable and the cable connector to reduce any substantialimpedance increase from occurring due to the cable termination.

The present invention is therefore directed to a termination structurefor providing improved connections between cables and connectors thatprovides a high level of performance and which maintains the electricalcharacteristics of the cable in the termination area.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providean improved termination structure for use in high-speed datatransmission connections in which the impedance discontinuity throughthe cable termination is minimized so as to attempt to better match theimpedance of the transmission line.

Another object of the present invention is to provide a terminationassembly for use in conjunction with signal cables that provides aconnection between the twisted wire pairs and grounding shield of thecable and the connector, the termination assembly having an improvedelectrical performance due to its structure, which eliminates largeimpedance discontinuities attributable to operator assembly.

A further object of the present invention is to provide an improvedtermination assembly for effecting a high-performance terminationbetween a transmission line having at least one pair of differentialsignal wires and an associated ground and a connector having at leasttwo signal and one ground terminal disposed adjacent to the signalterminals for contacting opposing corresponding signal ground terminals.

It is a further object of the present invention to provide such aconnector wherein, by varying the size of the ground terminal and itslocation relative to its two associated signal wires, the impedance ofthe connector may be “tuned” to obtain a preselected impedance throughthe connector.

Yet another object of the present invention is to provide a connectorfor connecting cables, such as those of the IEEE 1394 type, to a circuitboard of an electronic device, wherein the connector has a number ofdiscrete, differential signal wires and associated grounds equal innumber to those contained in the cables, the ground terminals of theconnector being configured in size and location with respect to thesignal terminals of the connector in order to minimize the drop inimpedance through the connector.

It is a further object of the present invention to provide a terminationassembly that provides a simple manner of termination for a signal cablein which the ground termination portion is both sized to control theimpedance through the termination and to provide a nest for thegrounding shield of the cable, the ground terminal portion of theconnector being located rearwardly of the signal terminal portions tothereby permit the facilitation of the cable termination with selectivestripping of the cable and minimal wire end preparation.

Yet still another object of the present invention is to provide atermination structure for a cable connector, the connector having aplurality of terminals, at least two of the terminals being signalterminals and one of the terminals being a ground terminal, each of theterminals having opposing contact and termination portions, thetermination portions having the form of hollow, curved cups the signalterminal termination portion cups being circumscribed by the groundterminal termination portion cup so that the ground terminaltermination-portion cup serves to orient the shield of the cable in apreferred orientation and to direct the placement of the signalconductors of the cable in the signal termination cups.

Yet it is still another object of the present invention to provide aconnector with a unique termination structure that is particularlysuitable for termination to cables, the termination structuremaintaining the mechanical arrangement of the cable conductors andgrounding shield as they enter the cable connector so that the signaland ground wires are maintained in an orientation that emulates that ofthe cable.

Yet another object of the present invention is to provide a connectorfor termination to a cable, wherein the ground terminal is positionedwithin the cable connector housing and spaced apart from two associatedsignal terminals in the connector housing, the ground terminal having abody portion that is larger than corresponding body portions of the twosignal terminal.

A yet further object of the present invention is to provide a cableconnector for use with differential signal wire pairs extending thelength of the cable, the cable connector having a ground terminal andtwo signal terminals that are arranged in a triangular orientationthroughout the connector and the termination area thereof.

In order to obtain the aforementioned objects, one principal aspect ofthe invention that is exemplified by one embodiment thereof includes afirst connector for a circuit board which has a housing having threeconductive terminals in a unique pattern of a triplet, with two of theterminals carrying differential signals, and the remaining terminalbeing a ground terminal. A second connector for a cable is provided thatmates with the first connector and this second connector also has atriplet pattern of conductive terminals that are terminated to signaland ground wires of the cable.

The arrangement of these three terminals within the connector permitsthe impedance to be more effectively controlled throughout the firstconnector, from the points of engagement with the cable connectorterminals to be points of attachment to the circuit board. In thismanner, each such triplet includes a pair of signal terminals that arealigned together in side-by-side order, and which are also spaced aparta predetermined distance from each other. A contact portion of theground terminal extends along a different plane than that of likeportions of the signal terminals, while the remainder of the groundterminal extends between the signal terminals, but along the same planeas the signal terminals.

The width of this ground terminal contact portion and its spacing fromthe signal terminals may be chosen so that the three terminals may havedesired electrical characteristics such as capacitance and the like,which affect the impedance of the connector. The width of the groundterminal is usually increased in the contact mating area of theterminals and may also be increased in the transition area that occursbetween the contact and termination areas of the terminals. By thisstructure, a greater opportunity is provided to reduce the impedancediscontinuity which occurs in a connector without altering the matingpositions or the pitch of the differential signal terminals. Hence, thisaspect of the present invention may be aptly characterized as providinga “tunable” terminal arrangement for each differential signal wire pairand associated ground wire arrangement found either in a cable or inother circuits.

In another principal aspect of the present invention, two or more suchtunable triplets may be provided within the connector housing, butseparated by an extent of dielectric material, such as the connectorhousing, an air gap, or both. In order to maximize the high speedperformance of such a connector, the signal and ground terminalspreferably all have similar, flat contacts that are cantilevered fromtheir associated body portions so that the ground terminal contactportions may be selectively sized with respect to their associatedsignal terminals to facilitate the tuning of the terminals to obtain theoptimum desired impedance in the connector system. When two such tripleterminal sets are utilized in the connectors of the present invention,power terminals of the connector may be situated between the two tripleterminal sets at a level equal to that of the ground terminals so as notto interfere with the signal terminals.

In yet another principal aspect of the present invention, the width ofthe ground terminal through the cable connector is varied so as topresent a different surface area that increases capacitive couplingbetween the ground and two differential signal terminals. This change inwidth occurs in the terminal body portion that is interposed between thecontact and termination portions of the terminals. The widths andsurface areas of the signal and ground terminals may be equal in thecontact areas because the cable connector terminals, when in contactwith the board connector, may take advantage of the differing widths andsurface areas of the board connector ground terminal contact areas. Thecable connector ground terminal body portion is then varied with respectto its associated signal terminal body portions to maintain a similardimensional relationship and spacing, preferably maintaining thetriangular orientation of the three terminals.

In still another principal aspect of the present invention, the cableconnector ground terminal termination portions are arranged asdemonstrated in another embodiment of the invention, in a triangularorientation to maintain the spatial relationships that occur among thesethree terminals in the terminal body portions that are housed in thecable connector. In the preferred execution of this embodiment, thetermination portions of all the terminals are curved to define hollow“nests” in receiving the cable wires therein.

Inasmuch as the size of the shield of the cable exceeds the size ofinternal wires, the ground termination nest is larger than the signaltermination nests. The nests are preferably positioned so as to maintainthe geometric relationship that exists between the signal wires andshield in the cable. The nests are preferably semi-circular to ensureaccurate positioning of the signal conductors and the shield in thetermination process. Thus, the ground terminal termination nest ispositioned to receive and contact the grounding shield of the cable,while orienting the two signal conductors as they appear in the cable tofacilitate the termination of them to the signal terminals of the cableconnector.

The grounding shield termination nest extends along a semi-circularextent. If an imaginary line is drawn to continue this extent, it willencompass and enclose the signal termination nests. The terminationportion nests may include extensions that extend outwardly and upwardlyfrom the terminals, although the main extent of these terminals occursin a general horizontal extent lengthwise out of the connector housing.These extents, as well as the center lines of the termination portionsare arranged in the aforementioned triangular relationship with theground terminal being spaced apart from and positioned above the twosignal terminals. These and other objects, features and advantages ofthe present invention will be clearly understood through considerationof the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of the following detailed description, reference will bemade to the accompanying drawings wherein like reference numeralsidentify like parts and in which:

FIG. 1A is an elevational view of a cable connector assembly of theinvention in place on a circuit board of an electronic deviceillustrating an “internal” environment in which the present inventionhas utility;

FIG. 1B is an elevational view of a cable connector assembly of theinvention in place on a circuit board of an electronic device andextending to the exterior of the device to illustrate an “external”environment in which the present invention has utility;

FIG. 2 is an exploded view of a cable connector in the form of a socketconnection constructed in accordance with the principles of the presentinvention that is suitable for mounting onto a printed circuit board andopening to either the interior or exterior of the electronic device;

FIG. 3 is a perspective view of the socket connector and inner shield ofthe connector of FIG. 2;

FIG. 4 is a perspective view of a cable with a plug connector terminatedthereto for engagement with the socket connector of FIG. 2;

FIG. 4A is an enlarged end view of the plug-style connector of FIG. 4,with a portion of the connector cover broken away to better illustratethe terminal structure and location thereof;

FIG. 5A is an enlarged detail view of a group of three terminalsarranged in a “triplet” and used in the connector of FIG. 2 illustratingthe relative size and placement of the two signal terminals and oneground terminal thereof;

FIG. 5B is an enlarged detail view of another type of terminal tripletthat may be used in the connector of FIG. 2;

FIG. 6 is an end view taken along lines 6—6 of FIG. 3, but illustratingonly the internal insulative body of the receptacle connector of FIG. 3;

FIG. 7 is a cross-sectional view taken along lines 7—7 of FIG. 3,illustrating the receptacle connector body and the separation of the tworows of terminals thereof;

FIG. 8A is a perspective view of a ground terminal utilized in thereceptacle connectors of FIGS. 2-3 and 6-7;

FIG. 8B is a perspective view of a signal terminal utilized in thereceptacle connectors of FIGS. 2-3 and 6-7;

FIG. 9A is a schematic end view of the connectors of FIGS. 2-4 and 6-7,illustrating the arrangement of the various terminals relative to eachother, and illustrating the use of two status information terminals;

FIG. 9B is a schematic end view of the connectors of FIGS. 12-14 and 17illustrating the arrangement and identification of the terminals andshowing the use of one status information terminal;

FIG. 9C is a cross-sectional view of two plug and receptacle connectorsshown in preliminary engagement with each other;

FIG. 10A is a perspective view of a ground terminal used in theplug-style connectors of the invention shown in FIGS. 4 and 12-14;

FIG. 10B is a perspective view of a signal terminal utilized in theplug-style connectors of the invention shown in FIGS. 4 and 12-14;

FIG. 11 is a diagram illustrating the typical impedance discontinuityexperienced with a high-speed cable connection and also the reduction inthis discontinuity that would be experienced with the connectors of thepresent invention;

FIG. 12 is a perspective view of multiple socket-style connector inincorporating a plurality of triplet terminal arrangements in accordancewith the principles of the present invention;

FIG. 13 is a schematic view of the connector interface area between acable and board connector;

FIG. 14 is a perspective view taken from the bottom of the rearterminating face of one embodiment of a cable connector illustrating atermination structure constructed in accordance with the principles ofthe present invention;

FIG. 15 is a perspective view of a set of three terminals used in theconnector of FIG. 14;

FIG. 16 is a top plan view of a cable with a stripped end in placewithin the termination portions of the terminals of the connector ofFIG. 14, illustrating the relative positions of the signal wires andgrounding shield of the cable;

FIG. 17 is a side elevational view of the termination assembly of FIG.16;

FIG. 18 is a sectional view of the termination assembly of FIG. 17 takenalong lines 18—18 thereof;

FIG. 19A is a cross-sectional view similar to FIG. 18, but schematicallyillustrating one positioning relationship of the signal and groundtermination portions of the connector terminals;

FIG. 19B is the same view as FIG. 19A, but schematically illustratinganother positioning relationship of the signal and ground terminationportions of the connector terminals;

FIG. 20A is a cross-sectional view taken through the terminationassembly and schematically illustrating one facet of the triangularrelationship among the signal and ground terminal termination portions;

FIG. 20B is a cross-sectional view similar to that of FIG. 20A, butillustrating another facet of the triangular relationship among thesignal and ground terminal termination portions;

FIG. 21 is a top plan view of another embodiment of a terminationassembly for a two-channel cable constructed in accordance with theprinciples of the present invention;

FIG. 22A is a cross-sectional view taken through the terminationassembly and schematically illustrating another facet of the triangularrelationship among the signal and ground terminal termination portions;

FIG. 22B is a similar cross-sectional view to that of FIG. 22A, butschematically illustrating another facet of the triangular relationshipamong the signal and ground terminal termination portions where thetriangle formed is a scalene triangle;

FIG. 22C is a similar cross-sectional view to that of FIG. 22A, butschematically illustrating another facet of the triangular relationshipamong the signal and ground terminal termination portions where thetriangle formed is an obtuse triangle;

FIG. 23 is a perspective view of the terminal assembly of a cableconnector constructed in accordance with the principles of the presentinvention with the terminals thereof shown in place upon an internalsupport structure;

FIG. 24 is a perspective view of the terminal structure of FIG. 23, buttaken from the underside thereof;

FIG. 25 is a longitudinal cross-sectional view taken through a cableconnector and schematically illustrating the signal and ground terminalsof FIGS. 23 and 24 in place within the cable connector housing;

FIG. 26 is a top plan view of another set of terminals suitable for usein the connectors of the present invention and illustrating theirrelative sizes and lengths;

FIG. 27 is a top plan view of a ground terminal used in the cableconnectors of the present invention with a signal terminal superimposedthereover in phantom; and,

FIGS. 28A-E are schematic views of the ground and signal terminal of thecable connector of FIG. 30, taken along lines A—A through E—E thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to an improved connector particularlyuseful in enhancing the performance of high-speed cables, particularlyin input-output (“I/O”) applications as well as other type ofapplications. More specifically, the present invention attempts toimpose a measure of mechanical and electrical uniformity on thetermination area of the connector to facilitate its performance, bothalone and when combined with an opposing connector.

Many peripheral devices associated with an electronic device, such as avideo camera or camcorder, transmit digital signals at variousfrequencies. Other devices associated with a computer, such as the CPUportion thereof, operate at high speeds for data transmission. Highspeed cables are used to connect these devices to the CPU and may alsobe used in some applications to connect two or more CPUs together. Aparticular cable may be sufficiently constructed to convey high speedsignals and may include differential pairs of signal wires, either astwisted pairs or individual pairs of wires.

One consideration in high speed data transmissions is signaldegradation. This involves crosstalk and signal reflection which isaffected by the impedance of the cable and connector. Crosstalk andsignal reflection in a cable may be easily controlled easy enough in acable by shielding and the use of differential pairs of signal wires,but these aspects are harder to control in a connector by virtue of thevarious and diverse materials used in the connector, among otherconsiderations. The physical size of the connector in high speedapplications limits the extent to which the connector and terminalstructure may be modified to obtain a particular electrical performance.

Impedance mismatches in a transmission path can cause signal reflection,which often leads to signal losses, cancellation, etc. Accordingly, itis desirable to keep the impedance consistent over the signal path inorder to maintain the integrity of the transmitted signals. Theconnector to which the cable is terminated and which supplies a means ofconveying the transmitted signals to circuitry on the printed circuitboard of the device is usually not very well controlled insofar asimpedance is concerned and it may vary greatly from that of the cable. Amismatch in impedances between these two elements may result intransmission errors, limited bandwidth and the like.

FIG. 11 illustrates the impedance discontinuity that occurs through aconventional plug and receptacle connector assembly used for signalcables. The impedance through the signal cable approaches a constant, orbaseline value, as shown to the right of FIG. 11 at 51. This deviationfrom the baseline is shown by the solid, bold line at 50. The cableimpedance substantially matches the impedance of the circuit board at 52shown to the left of FIG. 11 and to the left of the “PCB Termination”axis. That vertical axis “M” represents the point of termination betweenthe socket, or receptacle, connector and the printed circuit board,while the vertical axis “N” represents the interface that occurs betweenthe two mating plug and socket connectors, and the vertical axis “P”represents the point where the plug connector is terminated to thecable.

The curve 50 of FIG. 11 represents the typical impedance “discontinuity”achieved with conventional connectors and indicates three peaks andvalleys that occur, with each such peak or valley having respectivedistances (or values) H₁, H₂ and H₃ from the baseline as shown. Thesedistances are measured in ohms with the base of the vertical axis thatintersects with the horizontal “Distance” axis having a zero (0) ohmvalue. In these conventional connector assemblies, the high impedance asrepresented by H₁, will typically increase to about 150 ohms, whereasthe low impedance as represented by H₂ will typically decrease to about60 ohms. This wide discontinuity between H₁ and H₂ of about 90 ohmsaffects the electrical performance of the connectors with respect to theprinted circuit board and the cable.

The present invention pertains to a connector and a connectortermination structures that are particularly useful in I/O(“input-output”) applications that has an improved structure thatpermits the impedance of the connector to be set so that it emulates thecable to which it is mated and reduces the aforementioned discontinuity.In effect, connectors of the present invention may be “tuned” throughtheir design to improve the electrical performance of the connector.

Impedance Tunability

Turning to FIG. 1, one “internal” environment is depicted in which thepresent invention finds significant utility. In this environment, theconnectors of the present invention are disposed inside of the exteriorwall 108 of an electronic device, such as a computer 101. Hence, thereference to “internal.” The connectors of the present invention mayalso be used in an “external” application, as illustrated in FIG. 1B,wherein one of the connectors 110 is mounted to the circuit board 102,but extends partly through the exterior wall 108 of the device 101 sothat it may be accessed by a user from the exterior of the device 101.The connector assembly 100 includes a pair of first and secondinterengaging connectors, described herein as respective receptacle (orsocket) connectors 110 and plug connectors 104. One of these twoconnectors 110 is mounted to the printed circuit board 102 of the device101, while the other connector 104 is typically terminated to a cable105 that leads to a peripheral device.

FIG. 2 is an exploded view of a receptacle, or socket connector, 110constructed in accordance with the principles of the present invention.The connector 110 is seen to include an insulative connector housing 112that is formed from a dielectric material. In the embodiment depicted,the housing 112 has two leaf portions 114 a, 114 b that extend out froma body portion 116 of the housing 112. These housing leaf portionssupport a plurality of conductive terminals 119 as shown. In thisregard, the lower leaf portion 114 a has a series of grooves, or slots118, formed therein that are adapted to receive selected ones of theconductive terminals 119 therein. The upper leaf portion 114 b, hassimilar grooves 120 (FIGS. 6 & 7) that receive the remaining terminals119 of the connector 110.

In order to provide overall shielding to the connector housing 112 andits associated terminals 119, the connector may include a first shell,or shield, 123 that is formed from sheet metal having a body portion 124that encircles the upper and lower leaf portions 114 a, 114 b of thebody portion 116. This first shield 123 may also include foot portions125 for mounting to the surface 103 of the printed circuit board 102 andwhich provide a connection to a ground on the circuit board. Dependingfoot portions 107 may also be formed with the shield as illustrated inFIG. 1A for use in through-hole mounting of the connector 110, althoughsurface mounting applications are preferred as shown in FIG. 1B. Thefirst shield 123 may, as shown in FIG. 2, include retention members 126that are received within and which engage slots 127 formed in theconnector body portion 116.

The structure of the socket connector 110 illustrated in FIG. 2 permitsit to be used in the “internal” application shown in FIG. 1, as well asin “external” applications where the connector 110 is mounted to thecircuit board 102, but where the connector 110 extends partially throughand is accessible from an exterior wall 108 of the electronic device.

In order to prevent accidental shocks that may occur when a cable plugconnector is inserted into the socket of the receptacle connector 110, asecond shield 129 may be provided that extends over the first shield 123and which is separated therefrom by an intervening insulator element130. The second shield 129 also has mounting feet 131 integratedtherewith and will be connected to a chassis ground so that it isisolated from the circuit grounds. The second shield 129 preferably hasa length L₂ that is greater than the length L₁ of the first shell sothat it becomes difficult for user to contact the inner shield 123 whena cable connector is engaged with it.

As mentioned earlier, one of the objects of the present invention is toprovide a connector having an impedance that more closely resembles thatof the system (such as the cable) impedance than is typically found inmulti-circuit connectors. The present invention accomplishes this by wayof what shall be referred to herein as a tunable “triplet,” which is anarrangement of three distinct terminals shown at “A” in FIGS. 2, 5A, 5B& 6. In its simplest sense, and as shown in FIG. 5A, such a tripletinvolves two signal terminals 140, 141 and a single ground terminal 150that are arranged to mate with corresponding terminals of the plugconnector 104 that are terminated to the wires of a differential pair ofwires (preferably a twisted pair of wires) TPA+, TPA−, shownschematically in FIGS. 9A & 9B which carry the same strength signals butwhich are complements of each other, i.e., +1.0 volts and −1.0 volts aswell as a ground complement.

As shown best in FIG. 8B, the two signal terminals 140, 141 may have acantilevered design where each terminal 140, 141 has a surface mountfoot portion 142, a contact blade portion 143, and an interconnectingbody portion 144. With this design, the terminals 140, 141 may be easilystamped and formed. The terminals 140, 141 are received within slots 118of the lower leaf 114 b of the housing body portion 116 and may include,as shown in FIGS. 2 & 7, endtabs 145 at the free ends of the contactblade portions 143 that are received in openings 117 formed in theconnector housing body 116 at the ends of the slots 118. In order to“tune” the electrical characteristics of the connector and more closelyresemble the impedance of the system, a single ground terminal 150 isprovided in association with each set of differential signal terminals140, 141. Hence, the term “triplet.”

Each such ground terminal, as shown in detail “A” of FIGS. 5A, 5B and9A, 9B is associated with two differential signal terminals. Theschematic diagrams of FIGS. 9A and 9B illustrate the triple terminalconcept at “A” and “B”. In the embodiments illustrated, the groundterminal 150 is located on the upper leaf portion 114 b of thereceptacle connector body 116 and between the two signal terminals 140,141. In the schematic diagrams shown in FIGS. 9A & 9B, two such tripletsare shown in a triangular orientation, with the individual terminalsbeing identified with either an “A” or “B” suffix. Thus, TPA+ and TPA−represent the terminals for the differential signal wires of the “A”pair of wires, while TPA(G) represents the ground terminal for the “A”set of wires. Likewise, TPB+ and TPB− represent the terminals of thedifferential signal wires of the “B” pair of wires in the cable, whileTPB(G) represents the ground terminal of the “B” wire set.

This associated ground terminal 150, as shown in FIG. 8A, also has acantilevered design with a surface mount foot portion 152, anintermediate body portion 154 and a contact blade portion 153. As withthe signal terminals, the contact blade portion 153 of the groundterminal 150 lies in a different plane than that of its intermediatebody portion 154. As seen best in FIGS. 2, 8A-8B and 9C, the contactblade portions 143, 153 of the signal and ground terminals lie indifferent, but intersecting planes than their respective terminal bodyportions 144, 154. Although the preferred embodiment illustrates thesetwo planes as being generally perpendicular horizontal and verticalplanes, it will be understood that such planes need not beperpendicularly intersecting or lying in exact horizontal and verticalplanes to effect the advantages of the invention. It is desirable,however, that the two planes intersect with each other.

Still further, the surface mount portions 142, 152 of the signal andground terminals 140, 141, 150 may lie in a plane generally parallel tothat of their respective contact blade portions 143, 153. The mountingportions of the signal and ground terminals may also utilizethrough-hole members 195 (FIG. 1A) for mounting purposes. Theinteraction between the surface area and location of the ground andsignal terminals is explained below.

By this structure, each pair of the differential signal terminals of thecable or circuit have an individual ground terminal associated with themthat extends through the connector, thereby more closely resembling boththe cable and its associated plug connector from an electricalperformance aspect. Such a structure keeps the signal wires of the cable“seeing” the ground in the same manner throughout the length of thecable and in substantially the same manner through the plug andreceptacle connector interface and on to the circuit board. Thisconnector interface is shown schematically in FIG. 13. and may beconsidered as divided into four distinct Regions, I-IV, insofar as theimpedance and electrical performance of the overall connection assemblyor system is concerned. Region I refers to the cable 105 and itsstructure, while Region II refers to the termination area between thecable connector 104 and the cable 105 when the cable is terminated tothe connector. Region III refers to the mating interface existentbetween the cable connector and the board connector 110 that includesthe mating body portion of the connectors 104, 110. Region IV refers tothe area that includes the termination between the board connector 110and the circuit board 103. The lines “P, N, and M” of FIG. 11 have beensuperimposed upon FIG. 13.

The presence of an associated ground with the signal terminalsimportantly imparts capacitive coupling between the three terminals.This coupling is one aspect that affects the ultimate characteristicimpedance of the terminals and their connector. The resistance, terminalmaterial and self-inductance are also components that affect the overallcharacteristic impedance of the connector insofar as the triplet ofterminals is concerned. In the embodiment shown in FIG. 5B, the width D₂of the ground terminal blade portion 153′ is large enough so that itextends over portions of the signal terminals 140′, 141′. The largerwidth D₂ of the ground terminal blade portion 153′ has a larger surfacearea as compared to the signal terminal contact blade portions 143′ andhence presents a larger and overlapping contact mating area in theregion above the signal terminals 140′,141′.

In order to preserve the small “footprint” of the receptacle connector110 on the circuit board, the present invention reduces the width of theground plane in the ground terminal body portion 154′ as well as in thesurface mount foot portions 152′. By reducing the width of the groundterminal 150′ in its body portion 154′ in the second plane thereof sothat it may fit between the differential signal terminals, the distancebetween the signal terminals (TPA+ and TPA−) is also reduced to maintaina like capacitive coupling through the connector by maintaining apreselected substantially constant impedance between the ground terminaland the signal terminals. The impedance of the connector (as well as thecoupling between the terminals) is affected by the spacing between theadjacent signal terminals 140′, 141′ as well as between the signal andground terminals. Still further, the material used between theterminals, such as air, the housing material, or a combination of both,will present either a dielectric constant or a composite dielectricconstant in the areas between the signal and ground terminals.

By reducing the width of the ground terminal body portion 154′ in theembodiment of FIG. 5B, the overlapping aspect between the contact bladeportions 153′, 143′ of the ground and signal terminals stop in a firstplane (shown as horizontal), but no longer overlap in the second,intersecting (vertical) plane. Rather, in this second plane the groundterminal body portion 154′ is aligned with the signal terminals 144′ inan edge-to-edge arrangement. Although there is less cross-sectional areaof the ground terminal in these planes, the ground terminal is nowcloser to the signal terminals and hence like coupling between theterminals is maintained.

In the region of the first plane, namely that of the ground and signalterminal contact blade portions which lie in the mating interface ofRegion III of FIG. 18, the overall plate size of the ground terminal150′ is increased relative to that of the signal terminals 140′, 141′ tothereby selectively diminish the impedance as referred to above.Likewise, in the second plane, occupied by both the signal groundterminal body portions 144′, 154′, the spacing between the groundterminal 150′ and the signal terminals 140′, 141′ is reduced so that theground and signal terminals are brought closer together to therebyreduce the impedance of the connector. The signal ground terminalcontact blade portions 143, 143′ of the triplets are preferablymaintained in the same plane as illustrated in FIGS. 5A & 5B, and alongthe lower leaf portion 114 a of the connector housing 112. This notablypermits the impedance of the connector to be tuned from a spacing aspectbut also facilitates the mechanical engagement of the two connectors. Byproviding a ground terminal with a larger contact blade portion, themating contact between such terminals and the opposing ground and signalterminals of the other (plug) connector is improved withoutdetrimentally affecting impedance.

The effect of this tunability is explained in FIG. 11, in which areduction in the overall impedance discontinuity occurring through theconnector assembly is demonstrated. The impedance discontinuity that isexpected to occur in the connectors of the present invention is shown bythe dashed line 60 of FIG. 11. It will be noted that the magnitude ofthe peaks and valleys, H₁₁, H₂₂ and H₃₃ is greatly reduced. The presentinvention is believed to significantly reduce the overall discontinuityexperienced in a conventional connector assembly. In one application, itis believed that the highest level of discontinuity will be about 135ohms (at H₁₁) while the lowest level of discontinuity will be about 85ohms (at H₂₂). The target baseline impedance of connectors of theinvention will typically be about 110 ohms with a tolerance of about+/−25 ohms. It is contemplated therefore that the connectors of thepresent invention will have a total discontinuity (the differencebetween H₁₁ and H₂₂) of about 50 ohms, which results in a decrease fromthe conventional discontinuity of about 90 ohms referred to above of asmuch as almost 50%.

The tunability and impedance characteristics may also be affected, asstated earlier by the dielectric between the terminals. In this regard,and as shown best in FIG. 6, the lower leaf portion 114 a of theconnector housing 112 may itself be slotted, as at 160 to form an airgap 161 between halves of the lower leaf portion 114 a. Likewise, thesignal (and other) terminals 140, 141 or 140′, 141′ may be separatedfrom each other on the lower leaf portion 114 a by a similar air gap 162that is defined by a channel 163 formed in the lower leaf portion 114 a.These channels 163, as seen in FIG. 6, extend only partially through thethickness of the lower leaf portion 114 a so as to preserve thestructural integrity of the lower leaf portion.

Turning now to FIGS. 4 and 4A, an opposing mating connector 104 is shownin the form of a plug connector 170 that has an insulative connectorhousing 171 formed from a dielectric material in a complimentaryconfiguration to that of the receptacle connector 110 so as tofacilitate and ensure the proper mating therebetween. In this regard,the connector housing 171 has a base portion 172 with two portions 173that extend therefrom and which are separated by a gap 174 that servesas a keyway in the receptacle connector housing body key 134. This key134 of the receptacle connector may be found on the upper leaf portion,as shown in FIGS. 2, 3, 6 and 7, or it may be formed on the lower leafportion thereof as shown in FIGS. 9C and 17. The housing is hollow andcontains signal, ground and other terminals held in internal cavities ofthe housing 171 (not shown).

Two terminals are shown in FIGS. 10A and 10B which are representative ofthe type of terminal structure that is preferred for use in the plugconnector 110. FIG. 10A illustrates a ground terminal 180 having a flatbody portion 181 that interconnects a contact portion 182 to a wiretermination portion 183. The terminal 180 has a free end 184 which isreceived in a cavity 175 at the end of the connector housing 171. Thecontact portion 182 is bent at an upward angle so that it will projectout of a contact opening 176 in alignment with and in opposition to acorresponding ground terminal 150, or 150′, of the receptacle connector110.

The signal terminal 190 (FIG. 10B) is likewise structured and has a bodyportion 191 with a reduced width compared to that of the ground terminalbody portion 181 in order to effect coupling between the signal andground terminals. The body portion 191 interconnects a contact portion192 with a termination portion 193 and the contact portion 192 is alsobent at an angle to protrude through a corresponding opening 176 in theconnector housing 171. These openings and the terminal contact portionsappear on the lower surface of the connector base portion 172 as shownin FIG. 9C, and they are aligned with the terminal free end cavities 175that are shown in the front face of the connector housing 171.

The grounded signal terminals 180, 190 of the plug connector 170 (aswell as the other terminals) may be considered as “movable” contacts inthat they are deflected toward the center of the plug connector housing171 when the plug connector 170 is engaged with the receptacle connector110. The grounded signal terminals 140, 141, 150 (as well as the otherterminals) may be considered as “fixed” terminals because they do notmove during engagement and disengagement of the two connectors. In theschematic views of FIGS. 9A and 9B, the solid rectangles represent the“movable” terminals described above, while the dashed adjacentrectangles represent the “fixed” terminals as described above. TheseFigures, along with FIGS. 5A and 5B illustrate the triangularrelationship of the differential signal wires TPA+, TPA− with theirassociated ground terminal TPA(G). Each such terminal may be consideredas defining a vertex of a triangle that is formed when imaginary linesare drawn interconnecting adjacent terminals as shown by the dashedlines R in FIG. 9B. In this description and in the execution of theinvention, the ground terminal may be considered as being the apex, or“tip” of the imaginary triangle.

In a manner consistent with that set forth above with respect to theboard connector and its signal and ground terminals 140, 140′, 141, 141″and 150, 150′, the terminals 180, 190 of the cable connector 170 arealso structured to provide a desired impedance by way of their shapesand by way of the aforementioned triangular relationship.

As shown in FIGS. 10A and 10B, the ground and signal terminals 180, 190each have respective contact portions 182, 192 that engage opposingcontact portions 153, 143 of the ground and signal terminals 150, 140 ofthe opposing board connector 110. As shown in FIG. 9C, these cableconnector terminal contact portions 182, 192 have a length approximatelyequal to the corresponding lengths of the terminal contact portions 153,143 of the board connector 110. As might be expected; the widths andsurface areas of the cable connector ground terminal contact portion 182need not be increased because when the two connectors 110, 170 areengaged together, the geometry of the board connector contact portions153, 143 will dominate the mated connectors and the impedance formed asa result of the mating engagement that occurs in Region III in FIG. 18.

In order to continue this desired impedance and electrical performance,as shown in FIGS. 10A and 10B and as explained above, theinterconnecting body portion 181 of the ground terminal 180 is largerand preferably wider than one or both of the two signal terminalinterconnecting body portions 191. This increase in width increase thesurface area of the ground terminal at that area, i.e., the body portionof the connector, which increases capacitive coupling among the groundterminal 180 and its two associated signal terminals 190.

As shown in FIG. 9C, these terminals 180, 190 are also spaced apartalong their contact portions 182, 192, along their body portions 181,191 and, as illustrated by the solid rectangles of FIGS. 9A and 9B, arearranged in a triangular relationship with the cable connector groundterminal 180, and being located at the apex of the triangle. It can beseen that this triangular relationship will continue and maintain theelectrical balance of the connector system throughout the interface,from the circuit board to the cable. In the preferred execution of theinvention for this embodiment, the width of the ground terminal bodyportion 181 is preferably twice as wide as any single correspondingsignal terminal body portion 191. The body portion 191 of the signalterminal 190 in FIG. 10B is shown as having a somewhat slight triangularconfiguration at its rear part. This specific portion serves to provideengagement points with the connector housing 171 to hold the terminals190 in the connector housing 171 after molding. With this difference interminal geometries, the width and surface area relationships of theboard connector 110 may be likewise maintained in the cable connector105.

Cable Connector Termination

The dimensions and configuration of the termination portions of thecable connector terminals 180, 190 may also be structured to not onlymaintain the beneficial electrical relationship established within boththe cable 105 and the cable connector 104, but also to maintain theapproximate geometry of the cable 105 in the connector termination areaand to facilitate the termination of the cable 105 to such a connector104.

FIG. 14 depicts one such cable connector 600, and in particular, therear termination area 602 of the connector 600. The connector 600 has aninsulative housing 603 that may include cavities 604 disposed thereinthat house conductive terminals 605. These terminals include signalterminals 606, ground terminals 607 and other terminals such as powerterminals 608 and the like. The connector 600 is illustrated in FIG. 14is shown upside down from its usual configuration with the groundterminal being disposed on top as in FIG. 9C, in order to betterillustrate its associated signal terminals 606.

This embodiment of the present invention is directed in part tocontinuing the triplet relationship and configuration of the connectorsystem through the termination area of Region II in FIG. 13. In thisregard, two differential pair signal terminals 606 a, 606 b will beterminated to a corresponding pair of differential signal wires of thecable 105. A ground terminal 607 is associated with each suchdifferential signal pair terminals 606.

FIG. 15 illustrates a set of three terminals suitable for use in theconnector 600 of FIG. 14. This terminal set includes a pair of signalterminals 606 a, 606 b associated with a single ground terminal 607.Each terminal can be seen to include a deflectable contact portion 610,611 with a distal end 612, 613 for engaging a slot 715 formed in theconnector housing 603 (FIG. 25) and for holding the terminals in placetherein so that the terminals may be preloaded, if desired.Alternatively, the terminals free ends need not be confined in anymanner. The terminals 606, 607 have termination portions 614, 615 at theopposite, or proximal, ends of the terminals (when the point ofreference is taken from the rear end 602 of the connector 600.) Thesetermination and contact portions are interconnected by the correspondingsignal terminal body portion 619 body portions 618, 619. The groundterminal body portion 618 has a width W that is larger than thecorresponding widths of the two signal terminal body portions 619, andtherefore also has a larger surface area than the corresponding signalterminal body portion 618, in order to selectively decrease theimpedance in Region II. The ground terminal and body portions may alsoinclude conventional housing engagement portions, such as tangs 624 thatengage the connector housing.

For the discussion that follows, the termination portions 606, 607 arenot limited to the particular style connector shown, but may beconsidered as suitable for use as the termination portions 183, 193 ofthe terminals illustrated in FIGS. 10A and 10B.

As shown best in FIGS. 16-18, the termination portions 614, 615 arearranged to impose a measure of mechanical uniformity on the terminationof the connector, as well as attempt to maintain the electricaluniformity established by the triangular arrangement of the terminals inthe board connector 110 and the cable connector 600. In this regard, andas shown in FIG. 16, the ground terminal termination portion 614 andbody portion 618 are arranged between the respective signal terminationportions 615 when the assembly is viewed from the top or bottom. Whenviewed from the end, the ground termination portion 614 is spaced apartfrom the two signal termination portions 615 and these terminationportions may be considered as lying in distinct planes similar to thatdemonstrated in FIGS. 5A and 5B. No matter what planes the terminals liein, it is desired to maintain a triangular arrangement of the terminals.

This triangular relationship is shown diagrammatically in FIGS. 22A &22B. In FIG. 22A, three imaginary lines I₁₋₃ are drawn interconnectingthe centers of the three termination portions 614, 615. First, it mustbe noted that in FIGS. 16-18, 20A & B and 22A-C, the terminationportions 614, 615 are shown upside down from their normal orientation inorder to continue the ground-signal terminal arrangement of the typicalconnectors used to terminate the cable 105 to the circuit board 103. Inthis arrangement, as shown in FIGS. 5A-5B, the ground terminal 150,150′is disposed above its associated two signal terminals 140, 140′, 143,143′. This arrangement is continued in the cable connector 104, asillustrated in FIG. 9C. The imaginary lines I₁, I₂, I₃ drawn in FIGS.22A-C extend through the centers C of the termination portions 614, 615so that they intersect with each other. The resulting triangular may beequilateral as shown in FIG. 22A, or it may be a scalene triangle, withunequal length legs as shown in FIG. 22B or it may take the form of anobtuse triangle such as that shown in FIG. 22C. Other configurations mayalso be utilized.

Turning now to FIG. 23, it can be seen that the termination portions614, 615 of the terminals 607, 606 take the form of nests having hollow,semi-circular solder cups 620, 621. These nests, or solder cups 620, 621are formed integrally with their respective terminals terminatingportions 614,615 and may be considered as extensions thereby. Althoughthese extensions extend on a semi- or partly circular path asillustrated, they may take other extents, such as oval and rectangularfor example. The preferred semi-circular configuration assists inpositioning the cable wires properly in the termination assembly. As canbe seen in FIGS. 21-23, the interior radius R_(L) of the groundtermination nest 620 approximates of the outer radius R_(S) of the cableshield 650. As is conventional, the cable 105 includes a pair of signallines, with inner conductors 653 surrounded by insulation 652 and whichare both enclosed and in a ground shell 650, typically formed frombraided wire. A grounding drain wire 651 may run on the exterior of theshield 650 and the shield and drain wire are enclosed within an outerinsulative covering 657. The signal wires and their conductors 653typically include a differential signal pair that may be twisted alongthe length of the cable 105. No matter the extent of the twisting, thesignal wire pair will always be presented as shown in FIGS. 18-20B.

In FIGS. 18 and 20A, the signal conductors 653 are aligned with andspaced apart from each other so that they lie in a common plane P₁ (whentheir centers are connected by imaginary lines), although the line P₁that defines the plane in FIG. 20A is shown as extending along the basesof the signal termination solder cups. The signal lines may be slightlyoffset so that the two signal wire conductors 653 lie in two offsetplanes P_(1A) and P_(1B) as illustrated in FIG. 20B. In both suchinstances, the signal conductors 653 are encompassed by the shield 650and the termination portion 614 of the ground terminals 607 is spacedapart from the signal conductors and lies in a different plane P₂ inFIGS. 20A and 20B than that of the signal conductors 653. The soldercups 620, 621 taper down to the conventional rectangular or squareshapes of the termination portions 614, 615 after a predetermined lengththat follows the spacing and dimensional relationship of the boardconnector terminal sets 150, 140 and the plug connector terminal sets180, 190 in order to maintain the desired triangular orientation.

As illustrated in FIGS. 19A-B, the ground termination portion solder cup620 may have an extent such that it partially circumscribes the twosignal termination solder cups 621. This extent is preferably about 180degrees, and is shown in FIG. 19A where an imaginary line has been drawninterconnecting the free ends 625 of the ground terminal solder cup 620,and part of or all of the signal terminal solder cups 621 lie within thearea bounded by the ground solder cup 620 and its free ends 625.Similarly, such a partial circumscribing occurs in the structure of FIG.19B, where imaginary lines are drawn along the free ends 625 of theground terminal solder cups 620 so that they intersect. The signalsolder cups 621 are included within this angle θ.

The location of the ground and signal termination nests 620, 621provides one important advantage in the present invention. They serve tomatch and maintain the cable geometry and further facilitate thetermination of the cable to the cable connector 105. As shown in FIG.16, the cable 105 may have its outer insulation 657 that is stripped orcut to expose the shielding 650, drain wire 651 and signal lines. Thegrounding shield 650 need not be unbraided and twisted into a pigtail asin the past, but rather it may be trimmed, or cut, to a specific lengththat will provide sufficient contact with the ground termination portion614 and solder cup 620. Likewise, the signal line insulation 652 may bestripped to expose the signal line conductor 653. Such wire preparationmay be easily performed with a jig to maintain uniform terminationcharacteristics of the cable 105. Because the signal terminal portions615 and their associated solder cups 621 are arranged in a fashion thatpreferably matches that of the cable components, the solder cups andtermination portions of the connector 600 are able to present thedesired triangular configuration and maintain the cable grounding. Thelocation of the ground terminal termination portion 614 acts as abaseline guide upon which to orient and align the cable by way of itsgrounding shield so that the cable signal conductors are aligned withand in opposition with the signal terminal termination portions 615 ofthe cable connector

In instances where a drain wire 651 is used, the ground terminaltermination portion 614 may also include a drain wire nest 652.

As illustrated in FIG. 21, this termination arrangement may be used inmultiple channel connectors where two cables 105 a, 105 b are terminatedto a connector 700 and each cable 105 a, 105 b is dedicated to aparticular channel. Each termination assembly indicates a groundtermination nest 701 a, 701 b and signal termination nest 702 a, 102 bthat are separated by an intervening wall 704 formed as either part ofthe connector housing 700 or as a separate framework as shown in FIG.23. This intervening wall 704 affects the dielectric constant betweenthe two cables 105 a, 105 b and also prevents inadvertent shortingbetween the signal lines and the grounding shield of the two cables 105a, 105 b.

FIG. 23 illustrates a two-channel termination assembly 800 supported byan insulative framework 801. A connector housing (not shown) may bemolded over the framework and part of the terminals to form an integralconnector structure or it may be snapped into place by way ofinterlocking housing pieces. Each channel of the termination assemblyincludes one ground terminal 802 similar in general shape to the groundterminal 180 of FIG. 10A, and two signal terminals 803 that aregenerally similar to the signal terminals 190 of FIG. 10B.

Each ground terminal 802 has a contact portion 810 and a terminationportion 811 that has a pair of extensions 812 that extend outwardlythereupon to define a nest 813 with a curved configuration to receivethe shield 650 of the cable 105. The remainder of the ground terminationportions 811 extend in a plane that is spaced apart from the plane(s) inwhich one or both of the associated signal termination portions 830extend. The ground termination portion 811 of each channel is separatedby an intervening wall 820 that extends rearwardly from the framework801. As mentioned earlier, this wall assists in the preventing ofaccidental shorting from occurring between the two channels.

The ground terminals 803 include a body portion 813 that interconnectsthe termination portion 813 and contact portion 810 of the terminalstogether. As shown in the drawings, this body portion 813 is enlargedand has a width W_(ST) that is larger than the associated groundterminal contact portion 810. The point 815 where the body portion 813increases in its width may serve as an engagement surface against whichthe insulative material forming the framework 801 abuts to therebyassists in retaining the ground terminal 802 in place within theframework 801. This body portion 813 has a length L_(B) that extendsfrom the rear face 816 of the framework 801 to a point outside of theframework front face 817 as illustrated in FIG. 24. This ensures thatthe desired coupling occurs among the ground terminal 802 and its twoassociated signal terminals 803 through the connector housing. Thisincreased width part W_(ST) preferably occurs as a point, such asbetween “C” or “D” in the connector housing and shown in FIG. 25, thatis either at the end of the board connector ground terminal contactportions 153′ (FIG. 8A) or somewhat past the end of the of such contactsso that the wide portion of the ground terminals of each connectortriple either abut or overlap a bit so as to maintain the dimensionaland electrical relationship among the ground and signal terminals.

The two signal terminals 803 associated with the ground terminal 802 andmaking up a “triple” of the cable connector 104, have their terminationportions 830 spaced apart from the ground terminal termination portions813. These termination portions 830 include nests 835 for the conductorsof the 653 of the two associated signal wires. The insulation 652 ofthese wires may be stripped or trimmed back to a point where the exposedconductors 653 will project therefrom for a length that is preferablyequal to the length of the nests 835. These signal termination nests 835may be partially embedded in the framework 801 or the connector housingas illustrated in FIG. 24. In this regard, the framework 801 orconnector housing may be formed with slots or channels 831 that arealigned with and may serve as partial extension of the signaltermination portion nests. These slots 831 are also preferably separatedby intervening walls 832 that extend rearwardly a sufficient distancetoward the cable so as to provide a structure that will preventinadvertent contact between the two differential signal wires andthereby prevent shorting from occurring between them.

The signal terminals 803 take the general form as shown in FIG. 10B andinclude termination portions 830, contact portion 836 and body portion837 that interconnect the contact and termination portions together in asimilar manner as do the body portions of the ground terminals 802. Thebody portions 837 of these signal terminals 803 may include tangs 838that will engage the connector housing, preferably by embedding in themolding process.

FIG. 26 illustrates another form that the ground terminal 802 and thesignal terminals 803 may take, while FIG. 27 illustrates the signalterminal superimposed on the ground terminal in dashed lines. ThisFigure illustrates another form that the width relationship between theground and signal terminals may take. It can be seen that the groundterminal body portion is wider in its body portion that the body portionof the signal terminal and the ground terminal has a larger surface areathan the signal terminal in order to effect the aforementioned couplingaspect among the three terminals.

FIGS. 28A-E illustrate the relative spacing that occurs between theground terminal 802 and the signal terminals 803 in a cable connectorsuch along the longitudinal extent of the connector as shown in FIG. 25and which utilizes a cable termination assembly such as that illustratedin FIGS. 23 & 24. These Figures illustrate how the triangularrelationship is maintained throughout the connector. By manipulating thedistance between the ground and signal terminals 606, 607, the impedanceof the system may be changed, or “tuned.” This is done becausecapacitive coupling occurs between the two signal wires (and terminals)as well as each of the signal lines and the grounding shield (andterminals). The spacing of the terminals also affects the impedance ofthe system. The widths of the ground and signal terminals also affectsthe coupling and the impedance of the system, which also includes theresistance of the terminals, which in turn is also a function of thedimensions of the terminals.

While the preferred embodiments of the invention have been shown anddescribed, it will be apparent to those skilled in the art that changesand modifications may be made therein without departing from the spiritof the invention, the scope of which is defined by the appended claims.

We claim:
 1. A differential signal connector for mating with an opposing differential signal connector, comprising: a connector housing formed of an electrically insulative material; a triplet of conductive terminals disposed in said housing, the triplet including one ground terminal and two differential signal terminals associated with said ground terminal, each of the terminals including a contact portion for engaging a corresponding terminal contact portion of the mating connector, a termination portion for terminating said terminal to said grounding shield or differential signal terminals of said cable, and a body portion interconnecting said terminal and termination portions together, said body portions being at least partially supported within said housing; said grounding terminals and said differential signal terminals being arranged, from said contact portions thereof to said termination portions thereof, in a triangular orientation lengthwise throughout said connector, whereby said ground and signal terminal termination portions are disposed in a triangular configuration when said connector is viewed from a terminating end thereof.
 2. The differential signal connector of claim 1, wherein, said ground and signal terminals are arranged in a triangular configuration when said connector is viewed from a mating end thereof.
 3. The differential signal connector of claim 1, wherein, said signal termination portions are spaced horizontally apart from each other and said signal termination portions are spaced vertically apart from said ground termination portion. 